1 files changed, 104 insertions, 11 deletions

diff --git a/lib/Basic/SourceManager.cpp b/lib/Basic/SourceManager.cpp
index 156b809b51..dcbd4f166b 100644
--- a/lib/Basic/SourceManager.cpp
+++ b/lib/Basic/SourceManager.cpp
@@ -13,12 +13,15 @@
 
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/SourceManagerInternals.h"
+#include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/FileManager.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/System/Path.h"
 #include <algorithm>
+#include <string>
+
 using namespace clang;
 using namespace SrcMgr;
 using llvm::MemoryBuffer;
@@ -27,6 +30,75 @@ using llvm::MemoryBuffer;
 // SourceManager Helper Classes
 //===----------------------------------------------------------------------===//
 
+struct BufferResult::FailureData {
+  const llvm::MemoryBuffer *Buffer;
+  const char *FileName;
+  std::string ErrorStr;  
+};
+
+BufferResult::BufferResult(const BufferResult &Other) {
+  if (const llvm::MemoryBuffer *Buffer
+                        = Other.Data.dyn_cast<const llvm::MemoryBuffer *>()) {
+    Data = Buffer;
+    return;
+  }
+  
+  Data = new FailureData(*Other.Data.get<FailureData *>());
+}
+
+BufferResult::BufferResult(const char *FileName, llvm::StringRef ErrorStr,
+                           const llvm::MemoryBuffer *Buffer) {
+  FailureData *FD = new FailureData;
+  FD->FileName = FileName;
+  FD->ErrorStr = ErrorStr;
+  FD->Buffer = Buffer;
+  Data = FD;
+}
+
+BufferResult::~BufferResult() {
+  if (FailureData *FD = Data.dyn_cast<FailureData *>())
+    delete FD;
+}
+
+bool BufferResult::isInvalid() const {
+  return Data.is<FailureData *>();
+}
+
+const llvm::MemoryBuffer *BufferResult::getBuffer(Diagnostic &Diags) const {
+  llvm::StringRef FileName;
+  std::string ErrorMsg;
+  const llvm::MemoryBuffer *Result = getBuffer(FileName, ErrorMsg);
+  if (!ErrorMsg.empty()) {
+    Diags.Report(diag::err_cannot_open_file)
+      << FileName << ErrorMsg;
+  }
+  return Result;
+}
+
+const llvm::MemoryBuffer *BufferResult::getBuffer(llvm::StringRef &FileName, 
+                                                  std::string &Error) const {
+  if (const llvm::MemoryBuffer *Buffer
+                                  = Data.dyn_cast<const llvm::MemoryBuffer *>())
+    return Buffer;
+ 
+  FailureData *Fail = Data.get<FailureData *>();
+  FileName = Fail->FileName;
+  Error = Fail->ErrorStr;
+  return Fail->Buffer;
+}
+
+BufferResult::operator const llvm::MemoryBuffer *() const {
+  llvm::StringRef FileName;
+  std::string ErrorMsg;
+  const llvm::MemoryBuffer *Result = getBuffer(FileName, ErrorMsg);
+  if (!ErrorMsg.empty()) {
+    fprintf(stderr, "error: cannot open file '%s': %s\n",
+            FileName.str().c_str(), ErrorMsg.c_str());
+  }
+  
+  return Result;
+}
+
 ContentCache::~ContentCache() {
   delete Buffer;
 }
@@ -54,10 +126,13 @@ void ContentCache::replaceBuffer(const llvm::MemoryBuffer *B) {
   Buffer = B;
 }
 
-const llvm::MemoryBuffer *ContentCache::getBuffer(std::string *ErrorStr) const {
+BufferResult ContentCache::getBuffer() const {
   // Lazily create the Buffer for ContentCaches that wrap files.
   if (!Buffer && Entry) {
-    Buffer = MemoryBuffer::getFile(Entry->getName(), ErrorStr,Entry->getSize());
+    std::string ErrorStr;
+    struct stat FileInfo;
+    Buffer = MemoryBuffer::getFile(Entry->getName(), &ErrorStr,
+                                   Entry->getSize(), &FileInfo);
 
     // If we were unable to open the file, then we are in an inconsistent
     // situation where the content cache referenced a file which no longer
@@ -75,8 +150,21 @@ const llvm::MemoryBuffer *ContentCache::getBuffer(std::string *ErrorStr) const {
       char *Ptr = const_cast<char*>(Buffer->getBufferStart());
       for (unsigned i = 0, e = Entry->getSize(); i != e; ++i)
         Ptr[i] = FillStr[i % FillStr.size()];
+      return BufferResult(Entry->getName(), ErrorStr, Buffer);
+    } else {
+      // Check that the file's size and modification time is the same as 
+      // in the file entry (which may have come from a stat cache).
+      // FIXME: Make these strings localizable.
+      if (FileInfo.st_size != Entry->getSize()) {
+        ErrorStr = "file has changed size since it was originally read";
+        return BufferResult(Entry->getName(), ErrorStr, Buffer);
+      } else if (FileInfo.st_mtime != Entry->getModificationTime()) {
+        ErrorStr = "file has been modified since it was originally read";
+        return BufferResult(Entry->getName(), ErrorStr, Buffer);
+      }
     }
   }
+  
   return Buffer;
 }
 
@@ -426,12 +514,9 @@ SourceLocation SourceManager::createInstantiationLoc(SourceLocation SpellingLoc,
   return SourceLocation::getMacroLoc(NextOffset-(TokLength+1));
 }
 
-const llvm::MemoryBuffer *
-SourceManager::getMemoryBufferForFile(const FileEntry *File) {
+BufferResult SourceManager::getMemoryBufferForFile(const FileEntry *File) {
   const SrcMgr::ContentCache *IR = getOrCreateContentCache(File);
-  if (IR == 0)
-    return 0;
-
+  assert(IR && "getOrCreateContentCache() cannot return NULL");
   return IR->getBuffer();
 }
 
@@ -445,14 +530,22 @@ bool SourceManager::overrideFileContents(const FileEntry *SourceFile,
   return false;
 }
 
-/// getBufferData - Return a pointer to the start and end of the source buffer
-/// data for the specified FileID.
 std::pair<const char*, const char*>
-SourceManager::getBufferData(FileID FID) const {
-  const llvm::MemoryBuffer *Buf = getBuffer(FID);
+SourceManager::getBufferData(FileID FID, llvm::StringRef &FileName,
+                             std::string &Error) const {
+  const llvm::MemoryBuffer *Buf = getBuffer(FID).getBuffer(FileName, Error);
+  if (!Error.empty())
+    return std::make_pair((const char *)0, (const char *)0);
   return std::make_pair(Buf->getBufferStart(), Buf->getBufferEnd());
 }
 
+std::pair<const char*, const char*>
+SourceManager::getBufferData(FileID FID, Diagnostic &Diags) const {
+  const llvm::MemoryBuffer *Buf = getBuffer(FID).getBuffer(Diags);
+  if (!Buf)
+    return std::make_pair((const char *)0, (const char *)0);
+  return std::make_pair(Buf->getBufferStart(), Buf->getBufferEnd());
+}
 
 //===----------------------------------------------------------------------===//
 // SourceLocation manipulation methods.